Aspiration method

ABSTRACT

A method for the treatment of a stenosis or an occlusion in a blood vessel in which an occlusive device is first delivered and activated at a site distal to the occlusion to at least partially occlude the vessel. A therapy catheter is then introduced to treat the occlusion and a debris removal device is delivered to aspirate debris from the vessel. The present invention eliminates the need for a separate irrigation catheter and irrigation fluid which allows the procedure to be performed quickly and efficiently, and is especially useful in the removal of occlusion from saphenous vein graft, the coronary and carotid arteries, arteries above the aortic arch and vessels of similar size and pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/049,857, filed Mar. 27, 1998, now U.S. Pat. No. 6,135,991, which is acontinuation-in-part of U.S. patent application Ser. No. 08/813,807,filed Mar. 6, 1997, now abandoned, which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved method for aspiratingemboli, thrombi, and other types of particles from the human arterial orvenous system, the method being particularly well suited for treatingstenoses or occlusions within saphenous vein grafts, coronary arteries,arteries above the aortic arch such as the carotid and cerebralarteries, and similar vessels.

2. Description of the Related Art

Human blood vessels often become occluded or completely blocked byplaque, thrombi, other deposits, emboli or other substances, whichreduce the blood carrying capacity of the vessel. Should the blockageoccur at a critical place in the circulatory system, serious andpermanent injury, or even death, can occur. To prevent this, some formof medical intervention is usually performed when significant occlusionis detected.

Coronary heart disease is an extremely common disorder in developedcountries, and is the leading cause of death in the U.S. Damage to ormalfunction of the heart is caused by narrowing or blockage of thecoronary arteries (atherosclerosis) that supply blood to the heart. Thecoronary arteries are first narrowed and may eventually be completelyblocked by plaque, and may further be complicated by the formation ofthrombi (blood clots) on the roughened surfaces of the plaques.Myocardial infarction can result from atherosclerosis, especially froman occlusive or near occlusive thrombi overlying or adjacent to theatherosclerotic plaque, leading to death of portions of the heartmuscle. Thrombi and emboli also often result from myocardial infarction,and these clots can block the coronary arteries, or can migrate furtherdownstream, causing additional complications.

Various types of intervention techniques have been developed whichfacilitate the reduction or removal of the blockage in the blood vessel,allowing increased blood flow through the vessel. One technique fortreating stenosis or occlusion of a blood vessel is balloon angioplasty.A balloon catheter is inserted into the narrowed or blocked area, andthe balloon is inflated to expand the constricted area. In many cases,near normal blood flow is restored. It can be difficult, however, totreat plaque deposits and thrombi in the coronary arteries, because thecoronary arteries are small, which makes accessing them with commonlyused catheters difficult.

Other types of intervention include atherectomy, deployment of stents,introduction of specific medication by infusion, and bypass surgery.Each of these methods are not without the risk of embolism caused by thedislodgement of the blocking material which then moves downstream. Inaddition, the size of the blocked vessel may limit percutaneous accessto the vessel.

In coronary bypass surgery, a more costly and invasive form ofintervention, a section of a vein, usually the saphenous vein taken fromthe leg, is used to form a connection between the aorta and the coronaryartery distal to the obstruction. Over time, however, the saphenous veingraft may itself become diseased, stenosed, or occluded, similar to thebypassed vessel. Atherosclerotic plaque in saphenous vein grafts tendsto be more friable and less fibrocalcific than its counterpart in nativecoronary arteries.

Diffusely diseased old saphenous vein grafts with friableatherosclerotic lesions and thrombi have therefore been associated withiatrogenic distal embolic debris. Balloon dilatation of saphenous veingrafts is more likely to produce symptomatic embolization thandilatation of the coronary arteries, not only because of the differencein the plaque but also because vein grafts and their atheromatousplaques are generally larger than the coronary arteries to which theyare anastomosed. Once the plaque and thrombi are dislodged from thevein, they can move downstream, completely blocking another portion ofthe coronary artery and causing myocardial infarction. In fact, coronaryembolization as a complication of balloon angioplasty of saphenous veingrafts is higher than that in balloon angioplasty of native coronaryarteries. Therefore, balloon angioplasty of vein grafts is performedwith the realization that involvement by friable atherosclerosis islikely and that atheroembolization represents a significant risk.

Because of these complications and high recurrence rates, old diffuselydiseased saphenous vein grafts have been considered contraindicationsfor angioplasty and atherectomy, severely limiting the options forminimally invasive treatment. However, some diffusely diseased oroccluded saphenous vein grafts may be associated with acute ischemicsyndromes, necessitating some form of intervention.

There is therefore a need for improved methods of treatment for occludedvessels such as saphenous vein grafts and the smaller coronary arteries,the carotid and cerebral arteries, which decrease the risks to thepatient.

SUMMARY OF THE INVENTION

The present invention provides a novel method for removing plaque,thrombi, emboli and other types of obstructions or occlusions from bloodvessels having an inlet fluid pressure of at least 0.2 psi at any timeduring the diastolic/systolic cycle of the heart. Although the pressurewithin the vessel may fall below 0.2 psi during relaxation betweenheartbeats, so long as the pressure created by the heartbeat rises to atleast 0.2 psi, the pressure within the vessel will be sufficient. Themethod preferably includes the use of an occlusive device such as aballoon or filter to occlude the vessel distal to the obstruction, anoptional therapy catheter to treat the obstruction, and a source ofaspiration to remove the debris created by the therapy. By utilizing thefluid pressure and flow within the blood vessel, this method eliminatesthe need for a separate irrigation catheter and irrigation fluid. Thepresent invention allows for the removal of occlusions more rapidly thanknown methods. Speed is essential in such procedures, since blood flowis significantly decreased or stopped during the time the vessel isoccluded. The speed with which normal blood flow is restored is morecritical in main vessels which supply blood to collateral vessels. Themethod of the present invention allows for the removal of occlusionsfrom saphenous vein grafts, coronary arteries, arteries above the aorticarch such as the carotid and cerebral arteries, and blood vessels ofsimilar pressure. The minimally invasive treatment can be provided atlow cost and at relatively low risk to the patient.

In accordance with one aspect of the present invention, there isprovided a method for the treatment of a stenosis or an occlusion in ablood vessel having a fluid pressure of at least about 0.2 psi. Theblood vessel can be a saphenous vein graft, a coronary artery, a bloodvessel above the aortic arch, or any other vessel with a fluid flow rateof at least about 10 cc per minute (prior to occlusion of the vesselusing an occlusive device as described below), and more preferably,about 60 to 80 cc per minute, or about 120 to 140 cc per minute. Thisflow rate is needed to provide adequate irrigation fluid, which allowsfor substantially complete aspiration of the area surrounding theocclusion in a very short period of time. Using this combination ofirrigation provided from the blood flow into the vessel and aspiration,it has been found that aspiration of debris and fluid within the workingarea can occur in less than 3 seconds, but can also continue for 10 to20 seconds or longer, until the procedure is completed. Thus, thephysician can quickly and efficiently clear the debris from the area andrestore normal blood flow through the vessel.

One aspect of the method comprises first inserting a catheter orguidewire having an occlusive device at its distal end into the bloodvessel, until it is distal to the stenosis or occlusion. It is to beunderstood that the stenosis or occlusion could be in a discretelocation or diffused within the vessel. Therefore, although placement ofthe occlusive device is said to be distal to the stenosis or occlusionto be treated, portions of the diffuse stenosis or occlusion may remaindistal to the occlusive device.

Once in place, the occlusive device is activated to substantially orcompletely occlude the vessel distal to the existing stenosis orocclusion and to create a working area surrounding the stenosis orocclusion. A therapy catheter is then inserted into the blood vesseluntil it reaches the stenosis or occlusion, and a desired therapy isperformed on the stenosis or occlusion. The fluid inlet pressure withinthe vessel prevents any particles produced during therapy from flowingagainst the pressure and out of the working area, thus localizing theparticles for aspiration. The therapy catheter is removed, and thedistal end of an aspiration catheter or other device which creates anarea of turbulence and uses negative pressure to aspirate fluid anddebris is delivered into the vessel with the preferred placement beingat the working area in a position just proximal to the occlusive device.Fluid is aspirated from the working area inside the vessel preferablyproximal to the occlusive device to remove debris, while the fluidpressure within the vessel provides irrigation fluid within the workingarea. This aspiration creates a fluid flow within the working area, andprovides a flow of irrigation fluid into the area. It is thiscombination of irrigation and aspiration that allows for very fast andefficient removal of debris. Once aspiration is complete, the aspirationcatheter or similar device is removed and the occlusive devicedeactivated. Finally, the catheter or guidewire is removed from thevessel as well.

The insertion can include the act of inserting the proximal end of theguidewire into the hollow lumen inside the aspiration catheter andadvancing the aspiration catheter over the guidewire. This is commonlyknown as “over-the-wire” insertion. Alternatively, the proximal end ofthe guidewire can be inserted into a separate guidewire lumen on theaspiration catheter. Only a short portion of the aspiration catheter, aslittle as 5 cm, rides over the guidewire as the catheter is advanced.This is known as a single operator system, since, unlike theover-the-wire systems, a second operator is not required to hold thelong guidewire while the catheter is inserted into the patient; a singleuser alone can deliver the catheter over the guidewire in this system.

The distal end of the aspiration catheter or similar device should beslidably inserted into the vessel, across the occlusion and preferablyas close to the proximal side of the occlusive device as possible.Thereafter, aspiration is begun and the aspiration catheter should bepulled back by the operator, such that the distal tip slides proximal tothe occlusion and the occlusive device. Thus, while the distal tip ofthe aspiration catheter is preferably initially at a position distal tothe occlusion and no more than about 5 cm proximal to the occlusivedevice, or preferably no more than about 2 cm proximal to the occlusivedevice, the operator then slides the aspiration catheter back duringaspiration, crossing the occlusion and increasing the distance betweenthe distal tip and the occlusive device. Aspiration can therefore occuranywhere between about 0 to 20 cm proximal to the occlusive device.Alternatively, the distal tip of the aspiration catheter may beinitially positioned proximal to the occlusion and the occlusive device.Aspiration is begun, and the tip is moved in a distal direction, acrossthe occlusion and immediately adjacent the occlusive device. The tip isthen moved in a proximal direction, back across the occlusion. Thisdistal and proximal movement of the catheter tip during aspirationensures the complete removal of particles and debris from the patient.

The irrigation fluid supplied by the proximal portion of the bloodvessel will move any particles or debris from a position proximal to thedistal end of the aspiration catheter, thus allowing them to beaspirated. If a particle, however, is too far distal to the tip of theaspiration catheter, the irrigation fluid will tend to keep it there andnot allow it to be aspirated from the vessel. The tip of the aspirationcatheter can therefore be slidably advanced in a distal direction morethan once if desired, to ensure complete removal of debris. Onceaspiration has begun, additional blood will flow into the area, creatingturbulence and also allowing for the removal of debris.

If desired, a guide catheter can first be inserted into the patient'sbody to aid in the insertion of the guidewire and catheters. The guidecatheter can be used to provide aspiration in place of the aspirationcatheter if desired. The guide catheter is then removed followingcompletion of the procedure.

In accordance with another aspect of the present invention, there isprovided a method for the treatment of a stenosis or an occlusion in ablood vessel having a fluid pressure of at least about 0.2 psi, and afluid flow rate of at least about 10 cc per minute (when not occludedusing an occlusive device as described), and more preferably, about 60to 80 cc per minute, or 120-140 cc per minute. The method comprises thesteps of inserting a guidewire or catheter having an occlusive device onits distal end into the blood vessel, until the occlusive device isdistal to the stenosis or occlusion. The occlusive device is activatedto substantially occlude the vessel distal to the existing stenosis orocclusion and create a working area surrounding the stenosis orocclusion. A therapy catheter is then inserted into the lumen of anaspiration catheter or similar device, and the therapy catheter and theaspiration catheter are simultaneously delivered into the blood vesseluntil they reach the stenosis or occlusion. Therapy is performed toeliminate the occlusion, and the fluid pressure within the vessel actsto prevent any particles produced during therapy from flowing againstthe pressure and out of the working area. When therapy is complete, thetherapy catheter is removed while the aspiration catheter remains, andfluid inside the working area is aspirated to remove the particles whilethe fluid pressure provides irrigation fluid within the working area.When aspiration is complete, the aspiration catheter or similar deviceis removed and the occlusive device is deactivated. The guidewire orcatheter is also then removed.

In accordance with yet another aspect of the present invention, there isprovided a method for the treatment of a stenosis or an occlusion in ablood vessel having a fluid pressure of at least about 0.2 psi, and afluid flow rate of at least about 10 cc per minute (prior to occlusionusing an occlusive device). The method comprises inserting an occlusivedevice into the vessel until the occlusive device is distal to thestenosis or occlusion. The device can be attached to the distal end of acatheter or guidewire. The device is actuated to occlude the vesselsdistal to the existing stenosis or occlusion and create a working areasurrounding the stenosis or occlusion. The fluid pressure within thevessel prevents any particles dislodged during insertion of theguidewire or catheter from flowing against the pressure and out of theworking area. The distal end of an aspiration catheter or similar deviceis inserted to a position just proximal to the occlusive device, andfluid from the working area inside the vessel just proximal theocclusive device is aspirated. This will remove the stenosis orocclusion and any free particles while the fluid pressure providesirrigation fluid within the area. When aspiration is complete, theaspiration catheter is removed and the occlusive device deactivated. Theguidewire or catheter is then removed.

Another aspect of the present invention involves the use of anexpandable device, such as an inflatable balloon, to inhibit themigration of emboli or other particles in a proximal to distal directionwithin the vessel. This can be done by at least partially occluding thevessel at a site distal to the emboli or other occlusion. Again,although placement of the expandable device is said to be distal to theemboli or other occlusion to be treated, in the case of a diffuseocclusion, outlying portions of the occlusion may remain distal to thedevice.

The fluid pressure within the vessel prevents emboli or other particlesfrom migrating in a distal to proximal direction. If desired, a therapycatheter may be used to perform therapy on the vessel at the site of theemboli or occlusion. The therapy catheter may be removed, and acatheter, such as an aspiration catheter, having a lumen in fluidcommunication with a distal opening in the catheter is advanced acrossthe site of the emboli or occlusion such that the opening is distal toat least a portion of the emboli or occlusion. Fluid is then drawnthrough the distal opening in the catheter to remove the emboli,occlusion or debris. By drawing fluid into the opening, a fluid flow iscreated in the lumen of the catheter in a distal to proximal direction,while simultaneously, fluid flows in a proximal to distal direction inthe vessel.

In accordance with yet another aspect of the invention, there isprovided a method for the evacuation of emboli from a blood vessel. Acatheter having a lumen in fluid communication with a distal opening inthe catheter is positioned such that the opening is distal to at least aportion of an occlusive substance, such as emboli, within the bloodvessel. Fluid is then drawn from the vessel into the distal opening suchthat the emboli are carried from the vessel into the distal opening andthrough the lumen of the catheter. The fluid intake preferablysimultaneously creates a fluid flow in the lumen in a distal to proximaldirection, and in the vessel in a proximal to distal direction. Duringthe fluid intake through the catheter, the distal opening in thecatheter is preferably moved from a position distal to the occlusivesubstance, to a position proximal to the occlusive substance, to aposition distal to the occlusive substance to ensure complete removal ofparticles.

Accordingly, the present invention provides for very fast and efficientaspiration of an area surrounding an occlusion in a blood vessel. Thepatient's own blood provides the irrigation fluid, thereby eliminatingthe need for a separate irrigation catheter and supply of irrigationfluid. By reducing the number of devices needed to be inserted into thepatient, the present invention reduces the amount of time required tocomplete the procedure, and allows the physician to restore normal bloodflow in the vessel in a very short period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a human heart showing a saphenous veingraft used to bypass a portion of the coronary arteries.

FIG. 2 is a side view of an over-the-wire aspiration catheter inaccordance with the present invention.

FIG. 3 is a cross section of the aspiration catheter of FIG. 2, takenalong line 3—3 in FIG. 2.

FIG. 4 is a cross section of the aspiration catheter of FIG. 2 showing aguide wire over which the aspiration catheter rides.

FIG. 5 is a side view of a single operator type aspiration catheter inaccordance with the present invention.

FIG. 6 is a cross section of the proximal end of the aspiration catheterof FIG. 5, taken along line 6—6 of FIG. 5.

FIG. 7 is a cross section of the distal end of the aspiration catheterof FIG. 5, taken along line 7—7 of FIG. 5.

FIGS. 8A-C are side views of the various embodiments of the distal endof the aspiration catheter of the present invention.

FIG. 9 is a perspective view of an over-the-wire aspiration catheter andguidewire inserted into a saphenous vein graft in accordance with thepresent invention, with the vein graft shown partially cut away.

FIG. 10 is a schematic view of a catheter apparatus for use in themethod of the present invention;

FIG. 11 is a schematic cross-sectional view of a distal portion of thecatheter apparatus shown in FIG. 10.

FIG. 12 is a perspective view of an over-the-wire aspiration catheterand a guidewire bearing an occlusive filter inserted into a saphenousvein graft, with the vein graft shown partially cut away.

FIG. 13 is a perspective view of a therapy catheter delivering a drugand a guidewire having on occlusive device inserted into a saphenousvein graft, with the vein graft shown partially cut away.

FIGS. 14A-D show a perspective view of the movement of an over-the wireaspiration catheter during aspiration in a saphenous vein graft, withthe vein graft shown partially cut away.

FIGS. 15A-B illustrate the positioning of the occlusive device distal tothe occlusion in branching and non-branching blood vessels.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides an improved method for aspirating emboli,plaque, thrombi or other occlusions from a blood vessel. A preferredembodiment of the present invention is adapted for use in the treatmentof a stenosis or an occlusion in a blood vessel in which the stenosis orocclusion has a length and a width or thickness which at least partiallyoccludes the vessel's lumen. Thus, the method is effective in treatingboth partial and complete occlusions of the blood vessels. It is to beunderstood that “occlusion” as used herein, includes both complete andpartial occlusions, stenoses, emboli, thrombi, plaque, and any othersubstance which at least partially occludes the lumen of the bloodvessel.

The method of the present invention can be used to provide aspirationwithout the need for a separate irrigation catheter and irrigationfluid. In the context of removing plaque, thrombi or other blockagesfrom blood vessels, it has heretofore been proposed that an isolated“chamber” surrounding the occlusion be created prior to attemptingtreatment, and that separate irrigation fluid be provided through anirrigation catheter to the chamber. It has been surprisingly discoveredthat isolation of the occlusion is not required, and that the occlusioncan be successfully removed without the need for delivery of a separateirrigation catheter and irrigation fluid in those vessels where certainpressure and fluid flow conditions exist, such as saphenous vein grafts,coronary arteries, carotid arteries and other vessels.

In non-bifurcated areas of the blood vessels, it has been discoveredthat fluid from the collateral vessels or from the proximal portion ofthe same vessel acts as an infusion source. One can therefore occludeonly the distal portion of the vessel to create a working areasurrounding the occlusion and allow blood to flow from the proximalportion of the vessel into the working area. The area surrounding theocclusion is aspirated through the guiding catheter or aspirationcatheter. It should be noted that, as used herein, “proximal” refers tothe portion of the apparatus closest to the end which remains outsidethe patient's body, and “distal” refers to the portion closest to theend inserted into the patient's body.

The aspiration method is adapted for use in vessels in which nobifurcation or branching occurs for a distance of approximately 2-10 cmpast the site of the occlusion. Such a vessel 80 with an occlusion 82 isillustrated in FIG. 15A. This distance allows the vessel 80 to beoccluded using an occlusive device 84 without the risk of any particlesbeing carried downstream by the blood flow, where they could causefurther damage (as illustrated by the arrow in FIG. 15B). There areexceptions, however; for example, the internal and external carotidarteries. Here, the common carotid artery bifurcates into the internaland external carotid arteries. It is possible to occlude the internalcarotid artery only and allow particles to be carried away through theexternal carotid artery, since it is widely accepted that theseparticles can be carried safely away and will cause no damagedownstream.

The aspiration method can be used in any vessel of the body where thepressure is at least 0.2 psi at any time during the diastolic/systoliccycle of the heart, and preferably, is about 1.2 psi, with a flow rateof at least 10 cc per minute. Thus, although the pressure within thevessel may fall below 0.2 psi during relaxation between heartbeats, solong as the pressure created by the heartbeat rises to at least 0.2 psi,the pressure within the vessel will be sufficient.

A preferred embodiment of the method of the present invention isparticularly suited for use in removal of occlusions from saphenous veingrafts, coronary and carotid arteries, and vessels having similarpressures and flow where a suitable working area can be created. Asaphenous vein graft is depicted in FIG. 1. The graft 2 is used tobypass one of the occluded coronary arteries 4, and connects the aorta 6to the coronary artery at a location distal the occlusion 8. Althoughthe present invention will be described in connection with a saphenousvein graft, it should be understood that this application is merelyexemplary, and the method can be used in other blood vessels as well.

Apparatus Used

In a preferred embodiment of the method of the present invention, aguide catheter having a single lumen is first introduced into thepatient's vasculature through an incision made in the femoral artery inthe groin and used to guide the insertion of other catheters and devicesto the desired site. Following insertion of the guide catheter, anocclusive device is delivered to a position distal the occlusion. Forexample, a second catheter having an expandable device (referencenumbers 51 and 52, FIGS. 9 and 12), such as an inflatable balloon,filter, expandable braid or other mechanical occlusive device, attachedat its distal end is inserted through the guide catheter and past thesite of the occlusion (illustrated in FIGS. 9 and 12). The expandableocclusive device should be capable of preventing the migration ofparticles and debris from the working area, either through total orpartial occlusion of the vessel. Note that the occlusion of the vesselneed not be complete. Substantial occlusion of the vessel can besufficient for purposes of the present invention. The catheter should besized so as to be slidable with respect to the therapy and aspirationcatheters inserted over the catheter. The catheter is preferably made ofmetal such as stainless steel or nitinol, plastics, or composites. Aguidewire having an occlusive device on its distal end is also suitablefor use in the present method. The method can be effectively carried outusing a number of guidewires or catheters that perform the function ofoccluding the vessel and allowing for the slidable insertion of variousother catheters and devices. The term “catheter” as used herein istherefore intended to include both guidewires and catheters with thesedesired characteristics.

A preferred catheter for use to occlude the vessel is illustrated inFIGS. 10 and 11. The catheter apparatus 110 is generally comprised offour communicating members including an elongated tubular member 114, aninflatable balloon member 116, a core-wire member 120 and a coil member122. The catheter apparatus 110 is preferably provided with an outercoating of a lubricous material, such as TEFLON.

The body member 114 of the catheter apparatus 110 is in the form ofhypotubing and is provided with proximal and distal ends 114A and 114Bas well as an inner lumen 115 extending along the tubular member 114.The balloon member 116 is coaxially mounted on the distal end 114B ofthe tubular member 114 by suitable adhesives 119 at a proximal end 116Aand a distal end 116B of the balloon member 116 as in the manner shownin FIG. 11. The core-wire member 120 of the catheter 110 may becomprised of a flexible wire 120. The flexible wire 120 is joined bysoldering or brazing at a proximal end 120A of the flexible wire 120 tothe distal end 114B of the tubular member 114 as in the manner show inFIG. 11.

Preferably, the proximal end 120A of the flexible wire 120 has atransverse cross sectional area substantially less than the smallesttransverse cross-sectional area of the inner lumen 115 of the tubularmember 114. In the preferred embodiment, the flexible wire 120 tapers inthe distal end 120B to smaller diameters to provide greater flexibilityto the flexible wire 120. However, the flexible wire may be in the formof a solid rod or a helical coil or wire or combinations thereof.

As shown in FIG. 11, the distal end 120B of the flexible wire 120 issecured to a rounded plug 118 of solder or braze at the distal end 122Bof the coil member 122. The coil member 122 of the catheter 110 may becomprised of a helical coil 122. The coil member 122 is coaxiallydisposed about the flexible wire 120, and is secured to the flexiblewire 120 by soldering or brazing at about the proximal end 120A of theflexible wire 120 as in the manner shown in FIG. 11.

The balloon member 116 is preferably a compliant balloon formed of asuitable elastic material such as a latex or the like. The flexible coil122 is preferably formed of a wire of platinum based alloys. Theflexible core-wire 120 and the tubular member 114 are preferably formedof a nickel-titanium alloy.

Alternatively, the occlusion catheter can be configured so as to allowfor aspiration through the catheter, thus eliminating the need for aseparate aspiration catheter. In this embodiment, the catheter has along hollow shaft, having an outer diameter of less than about 0.038″,and preferably about 0.025″ to about 0.035″. The inner diameter or lumenof the shaft is about 0.020″ to about 0.030″. Aspiration occurs throughthe inner diameter of the catheter. The catheter has an occlusive deviceattached to its distal end. The occlusive device is preferably amechanical device such as a self-expanding braid or coil which acts as afilter, preventing particles from moving downstream. The catheter shaftfurther comprises at least one opening, and preferably several openings,located just proximal to the occlusive device, which allow foraspiration. The proximal end of the catheter is adapted to allow asource of negative pressure to be attached, such that it is in fluidcommunication with the inner lumen.

Once the guiding catheter and catheter have been properly positionedinside the vessel, the occlusive device at the distal end of thecatheter is actuated to occlude the vessel distal to the existingocclusion. A therapy catheter then is delivered to the site of theocclusion. The term “therapy catheter” is meant to include any of anumber of known devices used to treat an occluded vessel. For example, acatheter carrying an inflatable balloon for use in balloon angioplastycan be delivered to dilate the occlusion. Thermal balloon angioplastyincludes the use of heat to “mold” the vessel to the size and shape ofthe angioplasty balloon. Similarly, an intravascular stent can bedelivered via a balloon catheter and deployed at the site of theocclusion to keep the vessel open. Cutting, shaving, scraping orpulverizing devices can be delivered to excise the occlusion in aprocedure known as atherectomy. A laser or ultrasound device can also bedelivered and used to ablate plaque in the vessel. Various thrombolyticor other types of drugs can be delivered locally in high concentrationsto the site of the occlusion. It is also possible to deliver variouschemical substances or enzymes via a catheter to the site of thestenosis to dissolve the obstruction. The term “therapy catheter”encompasses these and similar devices.

After the therapy has been performed and the occlusion has been removedusing any of the methods and apparatus described above, the area isaspirated to remove fluid and debris. Aspiration can be provided throughthe guide catheter if desired. A source of negative pressure is attachedat the proximal end of the guide catheter, and fluid and debris areaspirated through the guide catheter's main lumen. Alternatively, anaspiration catheter or similar debris removing device is used to removeparticles and any other debris. The term “aspiration catheter” includesany device which creates an area of fluid turbulence and uses negativepressure to aspirate fluid and debris, and includes thrombectomycatheters, rheolitic devices and those devices which create a venturieffect within the vessel. Thus, it is possible that a single catheter isused as both the therapy catheter and the aspiration catheter. It shouldbe noted that any particles which break free during therapy andaspiration procedures will be kept at the site of the procedure by theocclusive device occluding the distal portion of the vessel incombination with the fluid pressure coming from the proximal portion ofthe vessel. The debris is prevented from migrating elsewhere, andremains localized for removal by aspiration.

An aspiration catheter particularly suited for use in the methoddescribed is illustrated in FIG. 2. The catheter 10 includes an adaptor14 and a seal 16 at its proximal end. The catheter 10 further includesan aspiration port 18 to which a source of negative pressure isattached. The aspiration catheter further comprises a long hollow shaft20 having a distal end 22. The distal tip 22 can include a radiopaquemarker to aid in locating the tip 22 during insertion into the patient,and is preferably soft to prevent damage to the patient's vasculature.

The aspiration catheter illustrated in FIG. 2 is an over-the-wirecatheter. As seen in FIG. 3, the catheter shaft 20 is hollow. Duringinsertion of the aspiration catheter 10, the proximal end of a guidewire26 is inserted into the distal end of the aspiration catheter 22, andthe aspiration catheter 10 is slidably advanced over the guidewire 26,which is positioned inside the hollow lumen 24 of the aspirationcatheter 10. The position of the guidewire 26 relative to the shaft 20of the aspiration catheter 10 is illustrated in FIG. 4, but of coursecan vary. For this type of aspiration catheter 10, a very long guidewire26, generally around 300 cm in length, is used to facilitate theinsertion of the aspiration catheter 10 over the guidewire 26.

Alternatively, the aspiration catheter 30 can be of a single operatordesign, as illustrated in FIGS. 5-7. The catheter 30 has an adaptor 32and an aspiration port 34 at its proximal end. Like the over-the-wireaspiration catheter 10, the single operator aspiration catheter 30further comprises a long hollow shaft 36 having a distal end 38. Thedistal tip 38 can include a radiopaque marker to aid in locating the tip38 during insertion into the patient, and is preferably soft to preventdamage to the patient's vasculature. At the distal end of the shaft 38,a guidewire lumen 40 is attached. This lumen 40 provides a separatelumen, apart from the main aspiration lumen 42 of the catheter 30, forthe insertion of the guidewire 26. This guidewire lumen can be as shortas 5 cm. As illustrated in FIG. 7A, during delivery of the aspirationcatheter 30, the proximal end of the guidewire 26 is inserted into thedistal end of the guidewire lumen 40, and the guidewire lumen 40 isslidably advanced over the guidewire 26. Unlike the over-the-wirecatheter 10 described above, only a short segment of the single operatoraspiration catheter 30 rides over the guidewire 26, and the guidewire 26remains in the guidewire lumen 40 and does not enter the aspirationlumen 42 of the aspiration catheter 30. With the single operator system30, the long guidewire 26 used with the over-the-wire catheter 10, andthe extra operator needed to handle it, are not required.

Although the guidewire lumen 40 is shown in FIG. 5 as being located onlyon the distal end 38 of the shaft of the aspiration catheter 36, thelumen 40 can also be made to extend the entire length of the shaft 36 ifdesired. In both embodiments, the aspiration lumen 42 is advantageouslyleft completely unobstructed to provide more efficient aspiration. Theguidewire lumen 40 can also include a slit in the outside wall of thelumen to facilitate faster and easier insertion and removal of theguidewire 26 through the side wall of the lumen, as shown in FIG. 7B.

In another embodiment not shown, the aspiration catheter can beconfigured such that the therapy catheter can be inserted through thelumen of the aspiration catheter. The aspiration lumen is made largeenough to accommodate the desired therapy catheter. This allows theaspiration catheter and the therapy catheter to be delivered into thepatient at the same time. When therapy is complete, the therapy catheteris removed while the aspiration catheter remains in place. Thiseliminates the need to separately deliver the aspiration catheter afterremoval of the therapy catheter, saving valuable time. It is preferablethat the size of the guide catheter used during this type of procedurebe sized from at least 8 to about 10 French to accommodate the size ofthe “over-the-therapy-catheter” aspiration catheter.

In yet another embodiment, also not shown, the therapy catheter can bebuilt over the aspiration catheter. For example, a dual-lumen catheterhaving a dilatation balloon at its distal end can be used. One lumen isused to inflate the dilatation balloon to be used for angioplasty, whilethe second lumen is used for aspiration. This design allows a singlecombined aspiration catheter and therapy catheter to be delivered intothe patient. When therapy is complete, aspiration is carried out withoutthe need to first remove the therapy catheter.

In the embodiment where the occlusion catheter is adapted to allowaspiration therethrough, no separate aspiration catheter is required.Once the occlusive device on the catheter is positioned distal to theocclusion, the occlusive device is activated to at least partiallyocclude the vessel. A therapy catheter is delivered and therapyperformed on the occlusion. Once therapy is complete, a source ofnegative pressure is provided at the proximal end of the occlusioncatheter, and aspiration occurs through the openings at the distal endof the catheter, just proximal to the occlusive device. Aspiration istherefore accomplished without the need for a separate aspirationcatheter, or removal of the therapy catheter.

FIGS. 8A, 8B, and 8C illustrate various embodiments of the distal end ofthe aspiration catheter. FIG. 8A shows the preferred tip 44, wherein theend has been angled. This tip 44 is also shown in FIG. 5. This angledtip 44 maximizes the area of aspiration. The distal tip of theaspiration catheter can also be blunt 45, as shown in FIG. 8B, or can betapered 46, with holes along the tip 47 to provide for aspiration, asillustrated in FIGS. 8C and 2.

Additional details relative to the catheters described above and theiruse are found in copending application Ser. No. 08/812,876, filed Mar.6, 1997, entitled “Hollow Medical Wires and Methods of ConstructingSame, now U.S. Pat. No. 6,068,623, application Ser. No. 08/858,900,filed May 19, 1997, entitled “Catheter for Emboli Containment System”,application Ser. No. 09/026,013, filed Feb. 19, 1998, entitled“Aspiration System and Method”, now U.S. Pat. No. 6,152,909, applicationSer. No. 09/026,225, filed Feb. 19, 1998, entitled “Balloon Catheter andMethod of Manufacture”, application Ser. No. 09/025,991, filed Feb. 19,1998, entitled “Syringe and Method for Inflating Low Volume CatheterBalloons”, abandoned, application Ser. No. 09/026,106, filed Feb. 19,1998, entitled “Occlusion of a Vessel”, now U.S. Pat. No. 6,312,407,application Ser. No. 08/975,723, filed Nov. 20, 1997, entitled “LowProfile Catheter Valve and Inflation Adaptor”, now U.S. Pat. No.6,050,972, and application Ser. No. 09/049,712, filed Mar. 27, 1998,entitled “Exchange Method for Emboli Containment”, all of which arehereby incorporated by reference in their entirety.

Method

The method of the present invention as used to remove plaque and anyassociated thrombi from a saphenous vein graft is described below inconnection with FIG. 9. Again, it should be noted that this applicationis merely exemplary, and that the method of the present invention can beused in other blood vessels and to remove other types of occlusions aswell.

A guide catheter (not shown) is introduced into the patient'svasculature through an incision in the femoral artery in the groin ofthe patient. The guide catheter has a single large lumen, and is used toguide the insertion of other catheters and devices. The guide catheteris advanced until it reaches the aorta and the ostium of the vein graft,where it will remain in place throughout the procedure. Fluoroscopy istypically used to guide the guide catheter and other devices to thedesired location within the patient. The devices are frequently markedwith radiopaque markings to facilitate visualization of the insertionand positioning of the devices within the patient's vasculature. Itshould be noted that at this point, blood is flowing through the vesselin a proximal to distal direction.

Next, an occlusive device is delivered to a site distal the occlusion.For example, a catheter or guidewire 50 having an occlusive device atits distal end is delivered through the guide catheter into thesaphenous vein graft 5 and past the site of the occlusion 56. In thisexample, the occlusive device is an inflatable balloon 52. The balloon52 is inflated to occlude the vein graft 5 at a site distal to theocclusion 56 to create a working area surrounding the occlusion. By“working area” is meant an area extending from the occlusive device in aproximal direction for a distance up to about 20 cm. The blood comingfrom the aorta enters the saphenous vein graft 5 and keeps any particles58 dislodged during the procedure from flowing proximally. In addition,the blood pressure and flow coming from the aorta provides theirrigation necessary for aspiration. As noted above, the blood pressurein the vessel is preferably at least about 0.2 psi, and the flow rate isat least about 10 cc per minute at some point during thediastolic/systolic cycle of the heart.

Once the vein 5 is occluded, a therapy catheter 150, as illustrated inFIG. 13, is delivered, if desired. The therapy catheter can be any of anumber of devices, including a balloon catheter used to performangioplasty, a catheter which delivers a stent, a catheter fordelivering enzymes, chemicals, or drugs to dissolve and treat theocclusion (as illustrated in FIG. 13), an atherectomy device, or a laseror ultrasound device used to ablate the occlusion. Alternatively, thetherapy catheter can be eliminated and use of the guide catheter or aseparate aspiration catheter alone can be used to aspirate theocclusion. This method is especially useful to remove emboli from thecoronary arteries following acute myocardial infarction, because theaspiration catheter can be made small enough to enter the coronaryarteries.

Once the desired therapy is performed, the therapy catheter is withdrawnfrom the patient's body and an aspiration catheter 60 is delivered overthe guidewire 50 and through the guiding catheter. The aspirationcatheter 60 rides over the guidewire 50 with the guidewire 50 insertedthrough the aspiration lumen 62 of the catheter 60. Alternatively, asingle operator type aspiration catheter can be used, in which only aportion of the aspiration catheter rides over the guidewire, which isinserted into a separate guidewire lumen. FIG. 9 illustrates thetreatment site during delivery of the over-the-wire aspiration catheter60 into the saphenous vein graft 5.

The treatment site during the aspiration procedure is illustrated inFIGS. 14A-D. The distal tip of the aspiration catheter 64 crosses thesite of the occlusion 56 and is initially positioned distal to theocclusion 56 and as close to the occlusive balloon 52 as possible,preferably less than about 5 cm, and more preferably less than about 2cm, from the proximal side of the balloon 52 (FIG. 14A). Thus, in oneembodiment, the distal tip of the aspiration catheter 64 is initiallypositioned immediately adjacent the occlusive balloon 52. Aspiration isbegun, and the operator moves the aspiration catheter in a proximaldirection, crossing the site of the occlusion 56 and increasing thedistance between the distal tip 64 of the catheter and the occlusiveballoon 52 (FIGS. 14B and 14C). During aspiration, the distal tip of theaspiration catheter 64 moves in a direction proximal to the balloon 52,crossing the occlusion 56, and continuing in a proximal direction for adistance that is preferably at least 1 cm proximal to the site of theocclusion 56. The distal tip of the aspiration catheter 64 may continueto be moved in a proximal direction away from the occlusion 56 for up to10 cm or more, or until the tip 64 reaches the guide catheter.Aspiration can therefore occur anywhere between about 0 to 20 cmproximal to the occlusive device 52. During aspiration, the flow offluid within the vessel is in a proximal to distal direction, whilefluid flow within the lumen of the catheter is in a distal to proximaldirection. If desired, the distal tip of the aspiration catheter 64 isthen again advanced across the occlusion 56 in the distal directionuntil it is again just immediately adjacent to the occlusive balloon 52(FIG. 14D). This movement of the tip of the aspiration catheter 64 in aproximal and distal direction can be repeated more than once to ensurecomplete aspiration of all debris.

In an alternate embodiment, the distal tip of the catheter 64 isinitially positioned proximal to the occlusion 56, preferably at least 1cm proximal to the occlusion 56. Aspiration is begun, and the distal tipof the catheter 64 is advanced in a distal direction across theocclusion 56 until the tip 64 is positioned immediately adjacent to theocclusive balloon 52. The tip of the catheter 64 is then moved in aproximal direction, back across the occlusion 56. Preferably, the tip ofthe catheter 64 continues in a proximal direction for a distance that ispreferably at least 1 cm proximal to the site of the occlusion 56. Asdescribed above, the distal tip of the aspiration catheter 64 cancontinue to be moved in a proximal direction away from the occlusion 56for up to 10 cm or more, or until the tip 64 reaches the guide catheter.This movement of the tip of the catheter 64 in a distal and proximaldirection can be repeated as often as desired to ensure complete removalof particles and debris.

The blood flow supplied by the aorta will move any particles 58 from aposition proximal to the distal tip of the aspiration catheter 64, thusallowing them to be aspirated, as illustrated by the arrows in FIG. 9.If a particle, however, is too far distal to the tip of the aspirationcatheter 64 (for example, more than about 2 cm), the blood pressure willkeep it there and not allow it to aspirated from the vessel 5. Theaspiration pressure can be increased, but not without the risk ofseverely damaging the vessel. Rather, this distal and proximal movementof the aspiration catheter, including placement of the tip immediatelyadjacent the occlusive balloon, will allow the user to completelycapture these distal particles. In addition, once aspiration has begun,additional blood will flow into the area adjacent and distal to the tipof the aspiration catheter, creating turbulence and allowing for thecomplete removal of debris.

A preferred source of negative pressure is any rigid containercontaining a fixed vacuum, such as a syringe, attached to the proximalend of the aspiration catheter at the aspiration port 34 (see FIG. 5). Amechanical pump or bulb or any other appropriate source of negativepressure can also be used. The difference between the existing pressurewithin the vessel and the aspiration pressure within the vessel shouldnot exceed about 50 psi. As noted above, if too much aspiration pressureis applied, the change in pressure in the vessel will be too great anddamage may occur to the vessel itself.

After the area inside the graft 5 is aspirated to remove any particles58 or other debris, the aspiration catheter 60 is removed. The balloon52 is deflated and the guidewire 50 and guiding catheter are removed.

As described above, the aspiration catheter can be sized such that itcan receive the therapy catheter within its lumen or the therapycatheter can be built over the aspiration catheter. In either case, theaspiration catheter and the therapy catheter are delivered over theguidewire and into the vein graft together. When therapy is complete,the therapy catheter can be removed if desired while the aspirationcatheter remains in place. When aspiration is complete, the aspirationcatheter, guidewire and guiding catheter are removed from the patient'sbody. Delivering the aspiration catheter and therapy catheter togethersaves time, which is critical during these types of procedures.Alternatively, the guide catheter can be used to provide aspirationthrough its main lumen.

In yet another embodiment, aspiration takes place through the lumen ofthe occlusion catheter or guidewire. The occlusive device on thecatheter is positioned distal to the occlusion, and the occlusive deviceis activated to at least partially occlude the vessel. The therapycatheter is delivered and therapy performed. A source of negativepressure is provided at the proximal end of the occlusion catheter, andaspiration occurs through openings located at the distal end of thecatheter just proximal to the occlusive device. This eliminates the needfor a separate aspiration catheter, and the need to remove the therapycatheter prior to aspiration. Again, this saves time, which is criticalduring these types of procedures.

While the foregoing detailed description has described severalembodiments of the apparatus and methods of the present invention, it isto be understood that the above description is illustrative only and notlimiting of the disclosed invention. It will be appreciated that thespecific dimensions of the various catheters and guidewires can differfrom those described above, and that the methods described can be usedwithin any biological conduit within the body and remain within thescope of the present invention. Thus, the invention is to be limitedonly by the claims which follow.

What is claimed is:
 1. A method of treatment of a blood vessel in whichblood fluid flows proximally to distally, said method comprising:delivering a guidewire having a proximal end and a distal end and anexpandable device thereon into the blood vessel, said expandable devicebeing actuatable between a nonexpanded state and an expanded state, saidexpandable device when in said expanded state forming a barriersufficient to inhibit emboli suspended in said fluid from migrating pastthe barrier in a proximal to distal direction; preventing emboli frommoving in a distal to proximal direction by exposing said expandabledevice to blood fluid pressure within said vessel; advancing a catheterhaving a lumen in fluid communication with a distal opening in thecatheter, said advancing comprising moving said distal opening relativeto said expandable device within the blood vessel such that said openingis distal to at least a portion of an occlusive substance within saidblood vessel, said occlusive substance comprising said emboli suspendedin said fluid; and drawing fluid from the vessel into the distal openingsuch that (a) a fluid flow is created in the lumen in a distal toproximal direction, and (b) said fluid flow is simultaneously created insaid vessel in a proximal to distal direction, whereby said emboli arecarried by said fluid flow from said vessel into said distal opening andthrough said lumen of said catheter.
 2. The method of claim 1, whereinthe occlusive substance includes material on a wall of the vessel. 3.The method of claim 2, wherein said advancing comprises moving saiddistal opening such that said distal opening is distal to at least someof the material on the wall of the vessel.
 4. The method of claim 1,further comprising moving the distal opening in the catheter relative tothe expandable device during said drawing of fluid.
 5. The method ofclaim 1, wherein said expandable device is an inflatable balloon.
 6. Themethod of claim 1, wherein said expandable device is a filter.
 7. Themethod of claim 1, further comprising advancing a guide catheter until adistal end of the guide catheter is positioned proximal to the emboli,and wherein said catheter is advanced through said guide catheter. 8.The method of claim 1, wherein said blood vessel comprises a saphenousvein graft.
 9. The method of claim 8, wherein said fluid pressure isprovided by blood from the aorta.
 10. The method of claim 1, whereinsaid blood vessel comprises a carotid artery.
 11. The method of claim 1,wherein the emboli are located in a segment of the blood vessel havingsubstantially no side branches.
 12. The method of claim 1, wherein thecatheter is advanced over the guidewire.
 13. A method for the evacuationof emboli from a blood vessel comprising: positioning an expandabledevice distal to a location in the vessel having an occlusion on thewalls of said vessel; positioning a catheter having a lumen in fluidcommunication with a distal opening in the catheter such that saidopening is distal to said location; drawing fluid from the vessel intothe distal opening such that emboli broken off from said occlusion arecarried by said fluid from said vessel into said distal opening andthrough said lumen of said catheter; and moving the distal opening inthe catheter until it is proximal to said location during the drawing offluid into the distal opening.
 14. The method of claim 13, whereinpositioning said expandable device further comprises delivering aguidewire into said vessel, said guidewire carrying said expandabledevice.
 15. The method of claim 14, wherein said catheter is positionedin the blood vessel over said guidewire.
 16. The method of claim 13,further comprising actuating said expandable device into an expandedposition prior to drawing fluid from the vessel.
 17. The method of claim13, wherein said drawing fluid further comprises creating a fluid flowin the lumen in a distal to proximal direction, and simultaneouslycreating fluid flow in the vessel in a proximal to distal direction. 18.The method of claim 13, wherein the distal opening in the catheter ispositioned distal said location more than once during the drawing offluid.
 19. The method of claim 13, wherein said expandable device is aninflatable balloon.
 20. The method of claim 13, wherein said expandabledevice is a filter.
 21. The method of claim 13, further comprising,prior to drawing fluid into the distal opening of the catheter,performing therapy on the occlusion, the performing of therapy causingemboli to break off from the occlusion.
 22. A method for the treatmentof an occlusion in a blood vessel having a fluid pressure of at least0.2 psi, comprising: inserting a guidewire having an occlusive device atits distal end into said blood vessel, until said occlusive device isdistal to said occlusion; activating said occlusive device to at leastpartially occlude said vessel distal to said occlusion and create aworking area around said occlusion; advancing a therapy catheter intosaid blood vessel until it reaches said occlusion; performing therapy onsaid occlusion; utilizing fluid pressure within said vessel to inhibitparticles produced during therapy from substantial migration in adirection proximal to said occlusion; removing said therapy catheter;delivering an aspiration catheter having a proximal end and a distal endover said guidewire until the distal end of said aspiration catheter isat a location proximal to the occlusive device and distal to theocclusion; creating a flow of fluid within said vessel in a proximal todistal direction by aspirating fluid from said working area inside thevessel through said distal end of said aspiration catheter, whereby saidparticles are removed from the working area and said fluid pressureprovides fluid to replace fluid aspirated from the working area; anddeactivating said occlusive device and removing said catheter.
 23. Themethod of claim 22, wherein said aspiration catheter comprises a hollowlumen and a separate second lumen for receiving said guidewire, andwherein said aspiration catheter is delivered by inserting a proximalend of said guidewire into said second lumen, and slidably advancingsaid second lumen of said aspiration catheter over said guidewire. 24.The method of claim 22, wherein said distal end of said aspirationcatheter is inserted at least one time to a position no more than about5 cm proximal to said occlusive device and thereafter slidably withdrawnin a proximal direction.
 25. The method of claim 22, wherein said bloodvessel is selected from the group consisting of a saphenous vein graft,a coronary artery, and a vessel above the aortic arch.
 26. The method ofclaim 22, wherein said blood vessel has a fluid flow rate of at leastabout 10 cc per minute.
 27. The method of claim 22, wherein said bloodvessel has a fluid flow rate of from about 60 to about 80 cc per minute.28. The method of claim 22, further comprising inserting a guidecatheter to aid in the insertion of said occlusive device and saidguidewire.
 29. The method of claim 22, wherein activating said occlusivedevice results in the vessel being substantially occluded.
 30. Themethod of claim 22, wherein said occlusive device is a balloon and saidactivating step comprises inflating said balloon.
 31. The method ofclaim 22, wherein said occlusive device is a filter and said activatingstep comprises deploying said filter to prevent migration of particlesdownstream.
 32. The method of claim 22, wherein performing said therapycomprises delivering a drug directly to the site of said occlusion. 33.The method of claim 22, wherein performing said therapy comprisescreating a venturi effect within said vessel to aspirate said occlusion,and wherein the fluid aspiration occurs simultaneously.
 34. The methodof claim 22, wherein performing said therapy comprises creating fluidturbulence within said vessel to aspirate said occlusion, and whereinthe fluid aspiration occurs simultaneously.
 35. The method of claim 22,wherein said therapy catheter is selected from the group consisting of athrombectomy catheter, a rheolitic device, and a device which creates aventuri effect within the vessel, and wherein the therapy and the fluidaspiration are performed simultaneously.
 36. The method of claim 22,further comprising moving the distal end of the aspiration catheterwithin said working area during aspiration.
 37. The method of claim 36,wherein the distal end of the aspiration catheter is moved in a distalto proximal direction during aspiration.
 38. The method of claim 36,wherein the distal end of the aspiration catheter is moved in a proximalto distal direction during aspiration.
 39. The method of claim 22,wherein the emboli are located in a segment of the blood vessel havingsubstantially no side branches.
 40. A method of treatment of a bloodvessel in which blood flows proximally to distally at a location havingan occlusion on the walls of said vessel that constricts said vessel,said method comprising: delivering a guidewire having a proximal end anda distal end and an expandable device thereon into the blood vessel,said expandable device being actuatable between a nonexpanded state andan expanded state, said expandable device when in said expanded stateforming a barrier sufficient to inhibit emboli in said blood frommigrating past the barrier in a proximal to distal direction; preventingemboli from moving in a distal to proximal direction by exposing saidexpandable device to blood flowing in a proximal to distal direction;advancing a catheter having a lumen in fluid communication with a distalopening in the catheter, said advancing comprising moving said distalopening relative to said expandable device within the blood vessel suchthat said opening is distal to said occlusion within said blood vessel;and drawing blood from the vessel into the distal opening such that (a)a blood flow is created in the lumen in a distal to proximal direction,and (b) said blood flow is simultaneously created in said vessel in aproximal to distal direction, whereby said emboli are carried by saidblood flow from said vessel into said distal opening and through saidlumen of said catheter.
 41. The method of claim 40, wherein saidadvancing comprises moving said distal opening such that said opening isdistal to at least some of the emboli.
 42. The method of claim 40,further comprising moving the distal opening in the catheter in a distalto proximal direction during said drawing of blood to cross at least aportion of the occlusion.
 43. The method of claim 40, wherein saidexpandable device is an inflatable balloon.
 44. The method of claim 40,wherein said expandable device is a filter.
 45. The method of claim 40,wherein said catheter is advanced over the guidewire.
 46. The method ofclaim 40, further comprising, prior to drawing blood into the distalopening of the catheter, performing therapy on the occlusion, theperforming of therapy causing emboli to break off from the occlusion.47. A method for the evacuation of emboli from a blood vessel in whichtherapy has been performed on a lesion in the vessel, comprising:positioning a catheter having a lumen in fluid communication with adistal opening in the catheter such that said opening is in the regionof said emboli; drawing fluid from the vessel into the distal openingsuch that emboli are carried by said fluid flow from said vessel intosaid distal opening and through said lumen of said catheter; and movingthe distal opening in the catheter relative to said lesion whilecontinuing to draw fluid into the distal opening.
 48. The method ofclaim 47, wherein the distal opening in the catheter is positioned at alocation distal to at least a portion of an occlusive substance withinsaid blood vessel.
 49. The method of claim 48, wherein the occlusivesubstance comprises emboli.
 50. The method of claim 48, wherein theocclusive substance includes material that is attached to the walls ofthe blood vessel.
 51. The method of claim 48, wherein the distal openingin the catheter is moved in a distal to proximal direction until it isproximal to said location while drawing fluid into the distal opening.52. The method of claim 51, further comprising moving the distal openingin the catheter in a proximal to distal direction after moving thedistal opening in a distal to proximal direction.
 53. The method ofclaim 47, wherein said catheter is delivered into the blood vessel overa guidewire.
 54. The method of claim 53, wherein the guidewire includesan occlusive device at its distal end.
 55. The method of claim 54,wherein the occlusive device is an inflatable balloon.
 56. The method ofclaim 54, wherein the occlusive device is a filter.
 57. A method for theevacuation of emboli from a blood vessel comprising: delivering aguidewire carrying an expandable device near its distal end to alocation in the vessel having an occlusion on the walls of the vessel;actuating said expandable device to inhibit emboli in said blood vesselfrom migrating past said expandable device; positioning a catheterhaving a lumen in fluid communication with a distal opening in thecatheter over said guidewire such that said opening is proximal to saidexpandable device; drawing fluid from the vessel into the distal openingsuch that emboli are carried by said fluid from said vessel into saiddistal opening and through said lumen of said catheter, and moving thedistal opening of the catheter during the drawing of fluid into thedistal opening in a direction such that the distal opening crosses atleast a portion of the occlusion.
 58. The method of claim 57, whereinthe expandable device is actuated at a location distal to the occlusion.59. The method of claim 57, wherein the distal opening of the catheteris moved during the drawing of fluid in a direction such that the distalopening crosses at least a portion of the occlusion.
 60. The method ofclaim 57, wherein the emboli are carried through said lumen of saidcatheter in a distal to proximal direction.
 61. The method of claim 57,further comprising, prior to drawing fluid from the vessel into thedistal opening, performing therapy on said occlusion, the performing oftherapy causing emboli to break off from the occlusion.
 62. The methodof claim 57, wherein the expandable device is an inflatable balloon. 63.The method of claim 57, wherein the expandable device is a filter. 64.The method of claim 57, wherein the distal opening of the catheter ismoved in a distal to proximal direction during the drawing of fluid. 65.The method of claim 57, wherein the distal opening of the catheter ismoved in a proximal to distal direction during the drawing of fluid. 66.The method of claim 65, wherein the distal opening of the catheter ismoved in a proximal to distal direction after moving the distal openingof the catheter in a distal to proximal direction during the drawing offluid.
 67. The method of claim 57, wherein the distal opening of thecatheter is moved over a distance of about 10 cm or more during thedrawing of fluid.
 68. The method of claim 57, wherein the distal openingof the catheter is moved repeatedly across the occlusion during thedrawing of fluid.